1. Field of the Invention
The present invention relates generally to a method for removing hydrocarbons from materials contaminated therewith and waste materials for recycling, and more particularly to a method for retorting organic matter in an essentially continuous closed system which is adaptable to various types of raw materials to be treated and which does not have a negative effect on the ecology.
2. Description of Prior Art apparatus for disposing of or treating waste materials and contaminated materials for recycling. Procedures have been utilized in the past for cleaning up contaminated materials and for recycling materials containing hydrocarbons. Such prior methods have included chemically treating the materials, burning the materials, disposing of the materials in landfills, and retorting the materials under high temperatures. Some examples of prior methods and apparatus as disclosed in the prior art are described as follows.
U.S. Pat. No. 3,682,115 to Rodgers, issued Aug. 8, 1972, discloses a portable disposal apparatus for combustible waste in which the combustible waste is crushed and chopped and conveyed to a combustion chamber where it is ignited with an auxiliary fuel and burned. Products of combustion which have not been fully consumed are condensed in condenser tanks. Unburned gases are then directed back into the combustion chamber to sustain combustion while residual tars, oils, and condensed liquids are removed from the condenser tanks from time to time.
U.S. Pat. No. 4,235,676 to Chambers, issued Nov. 25, 1980, discloses an apparatus including an elongated tube that is maintained at a temperature of about 1100 degrees Fahrenheit and through which organic waste material, such as shredded rubber automobile tires or industrial plastic waste or residential trash which preferably has metal and inorganic matter removed therefrom, is moved at a uniform rate of speed in the absence of air and/or oxygen. The vapors and gases which are produced and/or liberated within the tube are quickly removed therefrom by means of a vacuum of from about four inches to about six inches of mercury, with the vapors being condensed and the gases separated therefrom.
U.S. Pat. No. 4,308,103 to Rotter, issued Dec. 29, 1981, discloses a system including a cylindrical, horizontally disposed reactor vessel having a material conveying device including a plurality of paddle-like impellers mounted on a rotatable pipe for transporting comminuted solid carbonizable materials, such as coal, shredded scrap tires, comminuted municipal waste, sawdust and wood shavings, and the like, through the reactor vessel; a heating chamber arranged coaxially around the reactor vessel to subject the material passing through the reactor vessel to an indirect heat transfer relationship with a burning air-fuel mixture spirally swirling within the heating chamber and moving in a direction generally countercurrent to the material passing through the reaction vessel with the burning air-fuel mixture and combusted gases being progressively constricted and confined by the heating chamber. One end of the reaction vessel has a feed material inlet. Communicating with the feed material inlet is a gravity packed feed material column which assists in effectively sealing the feed material inlet from oxygen-containing gases. A rotary air lock is located near the upper end of the feed material column to further assure the exclusion of oxygen-containing gases from the interior of the reaction vessel. A side inlet may be provided in the feed material column for introducing inert gas to such column to further seal the system against oxygen-containing gases. The other end of the reaction vessel has a solid residue outlet and a gas-vapor outlet. Communicating with the solid residue outlet is a gravity packed column which contributes to the sealing at the outlet end of the reaction vessel from oxygen-containing gases. The comminuted solid carbonizable material passing through the reactor vessel is converted by pyrolysis, or high-temperature destructive distillation, into combustible gases, liquid hydrocarbons and solid carbonaceous residues. Gases and vaporized liquids generated from the solid carbonizable material introduced into the reaction vessel leave the reaction vessel through the gas-vapor outlet and are withdrawn under a slightly negative pressure and in a manner so as to avoid the entrance of any oxygen-containing gases into the reaction vessel.
U.S. Pat. No. 4,715,965 to Sigerson et al., issued Dec. 29, 1987, discloses a method for separating volatilizable contaminants from soil by introducing the soil into a rotary aggregate dryer through which a working gas indirectly heated to between 750 and 1800 degrees Fahrenheit is drawn to vaporize the contaminants, and for recovering the contaminants for disposal or for cooling the effluent to condense and precipitate out a substantial portion of the contaminants and passing the effluent through activated carbon.
U.S. Pat. No. 4,730,564 to Abboud, issued Mar. 15, 1988, discloses a multi-stage rotary kiln for burning waste and including a pair of concentric tubes affixed one inside the other with waste being conveyed through the inner tube and with hot burning gases being introduced into the inner tube to cause the waste to burn.
U.S. Pat. No. 4,821,653 to Jones, issued Apr. 18, 1989, discloses an apparatus for detoxifying heavy metals and the like contained in sludges, soils, incinerated ashes and similar materials by passing the metal-containing material through a pyrolyzer means operated with a substantially oxygen-free environment.
U.S. Pat. No. 4,974,528 to Barcell, issued Dec. 4, 1990, discloses a method for removing hydrocarbon contaminants from soil by advancing the soil through a dryer having a combustion chamber therein, and exposing the soil to a gaseous flame in the combustion chamber to volatilize certain of the contaminants in the soil.
The patents to Rodgers, Abboud and Barcell teach direct contact between a flame and the material being treated.
The patents to Chambers and Jones teach an anaerobic treatment.
The patent to Sigerson et al. teaches drawing a hot working gas stream at a temperature of between 750 degrees Fahrenheit and 1800 degrees Fahrenheit through the soil by an induced draft fan.
The patent to Rotter teaches moving a spiralling high temperature heating medium within the heating zone toward the material inlet end of the reaction pipe.